Background: National health organizations offer contrasting guidelines for women aged 40–49 regarding when to begin and how often to use mammography screening for breast cancer. The ACS recommends average risk women aged 40–44 receive annual screening “if they wish to do so” and annual screening for women aged 45–54. The United States Preventive Services Task Force recommends individualized screening for average-risk women before age 50 advised by risk assessment and shared decision-making (SDM). Clinicians lack guidance on how to conduct and what elements to include in mammography SDM. Our prior work identified core elements via scoping review applied to a modified Delphi consensus process involving patients, primary care physicians (PCP), and healthcare decision scientists (HDS). This study examines stakeholder group differences in endorsing core SDM elements. Methods: The Delphi consensus included 10 patients, 10 PCP, and 10 HDS and fielded 48 items to codify core elements of mammography SDM. A threshold of 80% agreement across all participants was set to establish consensus for retaining or dropping an item. In this study, separate stakeholder groups’ endorsement rates for each item were calculated. Items were deemed to have stakeholder discrepancy if one group differed from the 2 others in either meeting or not meeting the 80% threshold criteria. Results: 16 items (13 retained, 3 dropped in Delphi) had a discrepant group. For all retained items, the discrepant group fell below 80% criteria for retaining. For 2 of the dropped items, discrepant groups achieved threshold for retaining the item. One item was dropped despite most participants voting to retain it (>80%) due to the discrepant group’s rating <80%. Patients rated less importance to educating women about risks and recommendations. PCPs rated lower importance to training PCPs and women for discussions about mammograms and having discussions on a regular basis. HDSs rated greater importance to considering mammogram procedures and costs in SDM. Discussion: Leading healthcare organizations are increasingly recommending SDM in breast cancer screening, among other decisions. Guidelines enumerating core elements of SDM are needed to effectively direct clinicians. This study, by illuminating differences between stakeholder group perspectives, highlights the importance of eliciting varied perspectives in identifying core elements of SDM when informing healthcare practices and policy.